James Holmes, left, and defense attorney Tamara Brady appear in district court in Centennial, Colo., for his arraignment. / RJ Sangosti, The Denver Post, via AP

by Trevor Hughes, USA TODAY

by Trevor Hughes, USA TODAY

CENTENNIAL, Colo. -- James Holmes, accused of killing a dozen people and wounding scores more in a July shooting spree at a Colorado movie theater, pleaded not guilty by reason of insanity Monday.

Holmes sat silently in the courtroom as his attorneys received permission from Judge Carlos Samour Jr. to change his plea from a standard "not guilty." Samour set a May 31 hearing to decide if he will accept the insanity plea.

At the hearing, Samour also will advise Holmes of the rights he is giving up by pleading insane. Holmes could be warned that he faces interviews from state doctors and may also be given truth serum.

The trial is set for February, but could be delayed if Samour accepts the plea.

Defense attorney Dan King said the insanity plea was entered because defense experts have finished examining Holmes and rendered their opinions. He said experts needed the past two months to complete their work.

Under Colorado law, state doctors must decide if Holmes knew right from wrong, and even if he did, whether he was unable to stop himself due to mental illness.

"They can take into account almost anything that would bear on his state of mind," Maguire said. "This is art as much as it is science and medicine."

Maguire said it's rare for state doctors to rule someone not guilty by reason of insanity, which suggests Holmes' attorneys have already had their own expert examine him and are relatively confident in the outcome.

Maguire said no matter what the doctors in Pueblo rule, either the prosecutors or the defense will object to the finding, further delaying the case.

For Theresa Hoover, whose son AJ Boik, 18, was killed in the shooting, the question of Holmes' sanity has a simple answer. Hoover said Holmes' decision to stockpile weapons and ammunition in the months before the shooting makes that clear.

"What he did was nothing short of evil. He absolutely knew what he was doing was wrong," Hoover said. "I think he's evil, and there's a difference between evil and crazy. I don't think he's insane by any means."

Maguire said it's likely the state experts will agree with Hoover's assessment; he said the case ultimately will end in a conviction.What happens next, however, will be up to a jury.

Under Colorado law, death penalty cases have two phases. The first focuses on guilt or innocence. Then, jurors decide whether someone found guilty should be executed.

"Unless he's found insane, there's no way this isn't going to end in a conviction," Maguire said. "It's a horrendous crime, and a lot is going to depend on how this jury views him as a human being. Does the community see the need for death to bring justice?"